The present invention relates to a method of disposing obsolete planting seed treated with seed-protectant coatings, especially coatings comprising captan or any of the other widely used compounds such as, for example, pirimiphos-methyl [Actellic.RTM.] and thiram [TMTD.RTM.], alone or in combination with other fungicidally or even insecticidally active compounds. In France alone, the seed corn industry will generate 10,000 metric tons of obsolete treated seed corn 1990, equal to 10% of the total French seed corn market volume.
The planting seed industry has at present few options available for the disposal of obsolete treated planting seed that are acceptable by today's standards. An acceptable option would be one which is sound ecologically, safe, final and economical.
Nevertheless, each seed company has, or--at least until recently had--its own method of disposing of obsolete treated seed. These include various "detreatments", such as washing (which causes rinsate problems) [Coats and Dahm, 1979] or detreating by heat (which often proved to be of questionable effectiveness). In some countries, the seed treatment is washed off and the seed is fermented to produce bio-alcohol. Again, the question arises as to the fate of the rinsate. More recently, incineration joined the list of options. However, the demand for incinerator capacity is enormous and driving up the disposal cost.
Where rainfall patterns and cropping practices permit, obsolete treated seed corn is put to good use to produce green manure. This is currently being done in Switzerland. Of the above methods, green manure would appear to be the only one that can be considered acceptable. Nevertheless, its use is not possible where rainfall amounts are limited and where farmers do not traditionally use green manure in the crop rotation. In the South of France, Italy and Spain, where most of Europe's seed corn is produced, green manure could only be produced under irrigation, which is not economical.
It must be concluded that currently there is no universally practicable option to dispose, in an acceptable manner, of obsolete treated seed available to the seed industry. There is, therefore, a clear-cut need for an acceptable solution to this problem.